Dear Forum:
In diplomatese, the "Papal Ambassador" is officially known as the Apostolic Nuncio (previously/commonly known as the "Papal Nuncio.")
As recently as the last century, the Apostolic Nuncio, by comity, was elected, or ipso facto acted, as the Dean of the Diplomatic Corps of any given host country.
Currently, Apostolic Nuncios carry the dignity, at the least, of an Archbishop, as the slain Archbishop Courtney did. I stand corrected but I have not come across priests or monsignors acting or being appointed as Apostolic Nuncios.
Below is an excerpt from a communique from the Vatican Secretariat of State on the assasination of the Apostolic Nuncio to the Republic of Burundi:
Archbishop Michael Aidan Courtney, of Irish origin, was appointed apostolic nuncio of Burundi by His Holiness John Paul II on August 18, 2000. Previously, he had lent his inestimable collaboration in pontifical representations in South Africa, Senegal, India, Yugoslavia and Egypt. Before being appointed to Bujumbura, for almost five years he served as permanent observer of the Holy See to the Council of Europe at Strasbourg, France.
With the death of Archbishop Courtney, the list of missionaries who have given their life for the Gospel during 2003 grows longer. And now, for the first time, the name of a pontifical representative is added to that list of generous faithful. May the Lord grant them eternal rest!
As an aside, almost 60% of the total population of the East Central African republic of Burundi are Catholic.
May the Archbishop rest in eternal peace!
AmdG